Starting system for free



April 13, 1948. MEITZLER I 2,439,482

I STARTING SYSTEM FOR FREE PISTON ENGINES INVENTOR CZMM v AT TORNEY FIG.I

April 13, 1948.

D. E. MEITZLER Filed July 25, 1943 2 Sheets-Sheet 2 A5 fl /77% 7o 78 6s54 2e 56 60 I30 l L N 87 FIG. 2 94 k 5/ ||o I32 98 |os I06 IM I00 92 900 I22 I'NVENTOR I04 ATTORNEY Patentecl Apr. 13, 1948 UNITED STATESPATENT .OFFlCE STARTING SYSTEM FOR FREE PISTON ENGINES Donald E.Meitzler, Manchester, Conn., asslg'nor to United Aircraft Corporation,East Hartford, Conn., a corporation of Delaware Application July 23,1943, Serial No. 495,927 11 Claims. (Ci. 60- 14) This invention relatesto an engine starting mechanism and particularly to a starter forfreepiston engine-and-compressor units.

Conventional free piston engine and compressor units may be started byadmitting gas under pressure into a part of the unit, such as the airsprings. The volume and pressure of the gas admitted must be controlledin order to ase sure the necessary length of piston stroke. A feature ofthis invention is the automatic discharge into the unit of a measuredquantity of gas for starting.

In accumulator devices having a chamber in which the desired volume andpressure of gas is developed, the discharge of gas from the chamber hasbeen effected by manually cutting on the supply of gas to the device andopening the supply port to the atmosphere. A feature of this inventionis the automatic discharge of gas from the chamber as soon as thedesired pressure has been developed;

The co-pending Cooper application, Serial No. 495,926, filed July 23,1943, shows an accumulator valve having a storage chamber from which gasis released into the air spring of a free-piston engine-and-compressorunit for starting the engine. An object of this invention is to providean automatic control for that type of device.

Other objects and advantages will be apparent from the specification andclaims, and from .the accompanying drawings which illustrate anembodiment of the invention.

Fig. 1 'is a side elevation partly in section of a free-piston unitincorporating the starting mechanism.

Fig. 2 is a diagrammatic view of the starting mechanism. v

The unit shown includes an engine cylinder Ill having reciprocatingpistons l2 and Hi to which compressor pistons l6 and I8 in cylinders 20and 22 are integrally connected. Sleeves 24 and 26 attached to thecompressorpistons complete the reciprocating piston assemblies. The

sleeves in combination with stationary pistons 28 and 30 form air springcylinders.

The piston assemblies are moved apart by the burning of fuel injectedinto engine cylinder l8. Air compressed in the air spring cylinders onthe power stroke returns-the piston assemblies. These assemblies aremaintained at equal distances from the center of the engine cylinder bya linkage of which rods 32 and 34, extendin from the compressor, mayformapart. Intakemanifold 36 conducts air to intake valves 38 throughwhich air alternately enters opposite ends of the compressor cylinders.The compressed air leaves the cylinders through discharge valves 40,also at opposite ends of the compressor cylinders, and passes throughscavenge manifold 42 through ports 44 which. are uncovered by pistons l2and H at the end of the power stroke, thereby permitting air to be blownthrough the engine cylinder and exhaust ports 48 into exhaust manifold48. Valves 36 and 38 may be the type shown in Huff Patent No. 1,599,414,dated-September 14, 1926.

Starting .devices 50 and 52 for the unit are mounted in air springpistons 28 and it. The

devices are similar and only device 58 in piston This device in-,

28. will be described in detail. cludes a housing 54 held within piston28 by inter-engaging threads 56 and having accumulator or storagechamber 58, Fig. 2. This chamber has a port 60 communicating with theair spring cylinder and closed by a poppet valve 62. The stem 64 of thisvalve is slideable in a guide 66 in a cap 68 forming a part 01 housing54. Valve 62 closes port 60 by movement toward the storage chamber andis opened by movement away from the storage chamber, so that thepressure of the gas within the storage chamber assists in opening of thevalve, and pressure of gas in the air spring holds the valve closedduring operation of the unit.

Cap 68, which closes the end of chamber 58, has a bore forming a cylin-:r 10 which receives a piston 12 on the end of valve stem 64. The

inner end of cylinder 18 is connected with the device through conduit88, pressure beneath pis-- ton 12 assists spring 16 in keeping the valveclosed. Gas under pressure enters storage chamber 58 through restrictedchannel 14 and accumulates in the chamber.. The pressure of the gasacting on the piston (which is at least as large as the valve) and thepressure of spring 16 will keep the valve closed, since pressure in thestorage chamber cannot exceed the pressure on the piston.

After a suflicient pressure has been built up in the storage chamber,conduit 88 is opened to the atmosphere. This results in a. sudden dropin pressure on the piston holding the valve closed.

The pressure in storage chamber 58 acting on 3 valve 82 opens the valveand the gas stored in the chamber is discharged quickly through thevalve port into the air spring.

Throttling channel 14 is so proportioned that a negligible volume of gasescapes from the storage chamber into cylinder 18, while valve 82 isopen. As soon as the gas discharges from the chamber, the valve isclosed by spring 18.

In starting the free-piston unit, the engine pistonsare first moved tothe outer ends of their strokes. Gas is conducted from a source throughconduits 88 to starting devices 58 and 82. Release of pressure inconduits 88 causes a sudden inrushof compressed air from the valvemechanisms into the air sprin s which moves the engine pistons towardeach other, to the inner ends of their strokes.

The same action occur in'both air springs and the opposed pistons aresimultaneously moved toward each other. The storage chambers in the Q tothe outer ends of their strokes.

starting devices accommodate the required amount of gas for enginestarting without causing an excessive piston stroke. The valves areclwed immediately into the air springs and discharge of gas from the airsprings into the accumulator chambers is prevented during operation orthe engine.

Cap 68 has a transversely extending pin 82 which is notched at 88 inline with valve stem 84. The outer ends of pin 82 are flattened as shownat 88 to receive a wrench for turning the pin. When pin 82 is turned, itwill engage the end of valve stem 88 and open the valve for relievingpressure in the air spring. The structure of these starting devices isdescribed and claimed in the co-pending Cooper application, Serial No.-

495,926, filed July 23, 1943.

Either or both starting devices 88 and 52 may be controlled by anautomatically operating valve 81 which admits gas under pressure to thedevice and causes the poppet valve to open at a predetermined pressurein the storage chamber. Valve 81 includes a casing 88having a bore 89receiving a stationary sleeve 88 in which a valve plunger 82 is movable,the plunger being nor- 1 mally held in the position of Fig. 2 by a.spring 94.

Sleeve 88 is held within casing 88 by a clamping nut 86.

Casing 88 has a port 98 connected by a channel I88 and conduit I82 to asource of gas under pressure, an inlet control valve I88 admitting gasto valve 81 when desired.

Casing 88 also has a port W8 connected by conduit-88 to device 58. Anopposed port I88 may be connected by a similar conduit to device 52;.Plunger 92 has a groove H8 which, when the plunger is in normal positionshown, provides fluid connection between inlet port 98 and port I86,thereby directing gas from the source to the accumulator device.

Plunger 92 has another annular groove H2 which upon upward movement ofthe plunger establishes fluid connection from port I88 to one or morelarge discharge ports 4 in casing 88, these discharge portscommunicating with the atmosphere.

Plunger. 82 is automatically shifted from the position of Fig. 2 whenthe gas pressure in the accumulator chamber has reached a predeterminedvalue. Chamber 58 has a port H8 connected by a channel I28 and conduitI22 to a port I24 at the end of the valve plunger. This port has avalveseat I28 engaged by a valve I28 on the end of plunger 92. Valve I28 issmaller in diameter than the main part of the plunger and after thedischarge of gas 4 I when the plunger is raised from valve seat I26, gasfrom port I24-enters the plunger bore and causes an immediate motion' ofthe plunger against the action of spring 84. Adjustment of the tensionof spring 84 by a nut I38 controls the pressure at which the controlvalve 81 operates.

In operation, the engine pistons are first moved Gas is then admitted tovalve 81 by manually controlled valve I84. Gas entering valve 81 passesaround groove H8 and through port I88 to cylinder 18 of device 58. Gasreaches device 52 by port I88 in a similar way. Gas under pressurereaches storage chamber 58 through channel 14 which connects withcylinder I8. As gas pressure increases in chamber 58, the pressure inport I24 increases correspondingly until the pressure on the end orplunger 92 overcomes the action of spring 84 and moves plunger 82 toconnect port I88 to discharge port H4. This movement of plunger 92admits gas under pressure into the air springs (ii both devices 58 and52 are connected to valve 81), thereby moving the engine pistonsinwardlyto start the compressor unit. A manual valve I82 may be providedin conduit I22 for relieving the pressure in this conduit.

It is to be understood that the invention is not limited to the specificembodiment herein illustrated and described, but may be used in otherways without departure from its spirit as defined by the, followingclaims.

I claim:

1. An accumulator device having an accumulator chamber, a valve closinga port for said chamber and movable by pressure in the chamber actingdirectly on the valve for opening it, and means for holding said valveclosed against the pressure in said chamber, in combination with acontrol valve responsive to changes in pressure in said chamber forcutting on the supply of gas to said chamber and for releasing saidvalveholding means when pressure in the chamber reaches a predeterminedvalue.

2. An accumulator device having a chamber in which gas under pressure isstored, a valve closing a port for said chamber and movable by pressurein the chamber acting on the valve for opening it, a piston connected tosaid valve, and means for introducing gas to one side of said piston forholding said valve closed, in combination with a control valveresponsive to changes in pressure in the chamber for automaticallycutting off the supply of gas to said chamber and for releasing the gaspressure acting on the piston.

3. An accumulator device having a storage chamber, a valve closing aport for said chamber and movable by pressure in the chamber acting onthe valve for opening it, a cylinder, a piston movable in said cylinder,and connected to said valve, and means for directing gas under pressureto said ylinder for holding the valve closed in combination with acontrol valve responsive to pressure in said chamber and automaticallyoperative when pressure in the storage chamber reaches a predeterminedvalue for cutting off the supply of gas to the chamber and connectingthe cylinder to the atmosphere.

4. An accumulator device having a storage chamber, a valve closing aport for said chamber, a cylinder, a piston movable in said cylinder andconnected to said valve, means for directing gas under pressure to saidcylinder for holding the gas is supplied to said chamber, in combinationwith a pressure operated control valve responsive to pressure in thechamber and for connecting the cyllnder to the atmosphere when pressurein the storage chamber reaches a predetermined value and 'a fluidconnection from said chamber. to the control valve.

5. An accumulator device having a storage chamber, a valve closing aport for said chamber, and means for holding said valve closed againstthe pressure in said chamber, in combination with a control valvenormally directing gas to said chamber, and a connection from saidchamber to said control valve for operating said control valve to cutoff the supply of gas to the chamber and to release the valve-holdingmeans.-

6. In a control mechanism, an accumulator device having a ported chamberwith a valve closing the port, and a piston connected to said valve,pressure on the piston holding the valve closed, in combination with acontrol valve for holding the valve closed, and means for admitting gasfrom said cylinder to said chamber, in combination with a pressureoperated control valve responsive to changes in pressure in the chamberand automatically operative when pressure in the storage chamber reachesa predetermined value for cutting off the supply of gas to the cylinderand for connecting the cylinder to the atmosphere.

10. The combination with an accumulator devipehaving a chamber in whichgas is accumulated under pressure, and a valve closing the port for saidchamber, of a control valve for admitting gas under pressure to saidchamber and for causing said port-closing valve to open when thepressure in the chamber reaches a predetermined value, said controlvalve including a casing, a plunger slidable in said casing and movablefor controlling the flow of gas through said casing,

admitting fluid to said device for holding the valve closed andv forstoring fluid in said chamber, said control valve being movable inresponse to pressure in the chamber for cutting oif the supply of fluidto said chamber and for relieving the pressure on the piston.

7. In a control mechanism, an accumulator device having a ported chamberwith a valve closing the port, and a piston connected to said valve,pressure on the piston holding the valve closed, in combination with acontrol valve for admitting fluid to said device for holding the valveclosed and for storing fluid in said chamber, said control valve beingmovable to anotherlposition for relieving the pressure on the piston,and means associated with said valve and responsive to pressure changesin the chamber for shifting said valve from one position to the otherwhen pressure in the chamber reaches a predetermined value.

8. An accumulator device for use in starting a free-piston unit, saiddevice being connected to the air spring for admitting air underpressure to said spring, said accumulator device having a. storagechamber, a valve closing the port for said chamber, a cylinder, a pistonmovable in said cylinder and connected to said valve, and means fordirecting gas under pressure to said cylinder for holding the valveclosed, in combination with a pressure operated control valve responsiveto pressure changes in the chamber and automatically operative whenpressure in the storage chamber reaches a predetermined value forcutting off the supply of gas to the chamber and for connecting thecylinder to the atmosphere.

9. An accumulator device for use in starting a free-piston unit, saiddevice being connected to 1 the air spring for admitting air underpressure to said spring, said accumulator device having a storagechamber, a valve closing the port for said chamber, a cylinder, a pistonmovable in said cylinder and connected to said valve, means foradmitting gas under pressure to said cylinder i'or a. fluid connectionfrom the chamber to one end of the casing whereby the pressure in thechamber is transmitted to the end of the plunger and 1 a spring urgingthe plunger against the pressure acting on said plunger.

11. The combination with an accumulator device having a chamber in whichgas is accumulated under pressure and a valve closing the port for saidchamber, of a control valve for admitting gas under pressure t o saidchamber and for causing said port-closing valve to open when thepressure in the chamber reaches a predetermined value, said controlvalve including a casing, a plunger slidable in said casing and movablefor controlling the flow of gas through said casing, a fluid connectionfrom the chamber to one end of the casing whereby the pressure in thechamber is transmitted to the end of the plunger, a. spring urging theplunger against the pressure acting on said plunger and means foradjusting the effect of the spring for controlling the pressure at whichthe plunger will move,

DONALD E. MEITZIER'.

REFERENCES orrnn UNITED STATES PATENTS Number Name Date 387,256 PrattAug. '1, 1888 1,646,640 Daniel Oct. 25, 1927 1,763,426 Fraser June10,1930 1,799,914 Lemoine Apr. 7, 1931 1,918,341 Knaak July 18, 19332,168,828 Pateras Pescara Aug. 8, 1939 2,215,326 Janicke Sept. 1'1, 1940FOREIGN PATENTS Number Country Date 11,138 Great Britain A118. 11, 188414,413 Great Britain June 23, 1906 225,397 Great Britain Dec. 4, 1924

